The present invention pertains to a sandwich component, which comprises at least two massive metallic sheet metal parts located opposite each other and a metal powder layer arranged between the sheet metal parts, which is to be expanded as well as to a process for manufacturing the sandwich component.
Sandwich components of the type described in the introduction are used in various areas of industry and especially in vehicle manufacture, because they have a relatively low weight at high rigidity.
The process for manufacturing such sandwich components is usually carried out in a plurality of steps. A sandwich blank is first manufactured from massive metallic sheet metal plate parts and the metal powder layer, e.g., by a roll-bonding operation. The rolling operation brings about a metallic bonding between the middle metal powder layer and the inner sides of the massive metallic sheet metal plate parts covering this metal powder layer. After the conclusion of the rolling operation, the sandwich-like plate material can be separated into individual parts by punching, and a changed shape is subsequently imparted to the individual to parts, e.g., by deep-drawing or similar processing steps. Certain boundary conditions, which are patented, e.g., in DE 196 12 781 C1, are to be complied with in this connection. It is described in that document that after the shaping of the sandwich-like shaped blank, this blank is introduced for the final manufacture into an expanding mold adapted with one wall to its end-contoured side and is subjected to a heat treatment in a suitable manner. Due to the fact that an expanding agent is added to the metal powder layer, expansion of the metal powder layer is brought about by the thermal effect. This expansion operation is terminated when the second massive metallic cover layer has come to lie on the second contact surface of the expanding mold.
Due to the above-described sequence of the manufacturing steps, it is possible to manufacture lightweight metallic components for a constantly dimensionally accurate quantity production, especially in vehicle manufacture, from flat, sandwich-like shaped blanks.
Moreover, manufacturing processes in which metal powder is expanded in a corresponding mold and the blank thus manufactured is later introduced into a casting mold and is subsequently finished, e.g., by diecasting into a sandwich component with an expanded core and an outer, massive metallic shell, are known from the state of the art. Such a manufacturing process has been known, e.g., from DE 195 01 508 C1.
Even though the various above-described manufacturing processes make it possible to manufacture sandwich components which make possible increased energy absorption compared with massive components and have a substantially better damping because of the acoustic conditions, a special partial stiffening of the sandwich components to provide increased rigidity adapted to the external conditions is not possible with the processes described. Rigidity is not possible because additional reinforcing elements would have to be introduced only in certain cross sections of the sandwich component. The introduction of such reinforcing elements is possible according to the state of the art only by means of welded and riveted constructions. Using such process steps, it is possible to introduce reinforcing elements between two massive metallic cover layers and to lock them in a positive-locking manner. However, such a manufacturing process is complicated in terms of the production technology and is associated with increased manufacturing costs as a result.
The technical object of the present invention is therefore to improve a sandwich component of this type such that the increased requirements, especially in the automobile manufacturing technology, in terms of increased rigidity, are met with a reduced weight of the component and to provide a process for manufacturing same.
This technical object is accomplished according to the present invention by the sandwich component having additional reinforcing elements in individual cross-sectional areas, which reinforcing elements are connected in a positive-locking manner to the expanded metal powder layer surrounding them, which said metal powder layer is in turn connected to the outer, massive metallic sheet metal parts in such a way that it cannot be detached without destruction.
This special design makes it possible, for the first time ever, to optimally adapt the moments of resistance opposing the special stresses occurring within chassis components corresponding to these special stresses. This can be achieved, on the one hand, by the different designs of the inner reinforcing elements by manufacturing these, e.g., from square profiles, flat materials or U profiles. Moreover, it is possible to correspondingly adapt the material of the reinforcing elements, so that, e.g., even materials such as titanium or the like may be used in the reinforcing elements for the highest stresses.
The process according to the present invention for manufacturing such sandwich components makes possible, compared with the state of the art, the design of the sandwich components according to the present invention in the first place; moreover, the manufacturing process is characterized by the sequence of simple and inexpensive process steps. The process for manufacturing a sandwich component, which requires for the manufacture at least two mutually opposite sheet metal parts and an expandable metal powder layer arranged between the sheet metal parts, is specifically described by the process steps of providing a massive metallic sheet metal part each with a metal powder layer, of subsequently arranging the two sheet metal parts with their sides provided with the metal powder layer facing one another one on top of another, and of finally heating the sheet metal parts lying one on top of another by supplying heat such that a melting process is brought about in the metal powder layers facing one another due to the supply of heat, which melting process brings about an undetachable connection of the metal powder layers.
Thus, a xe2x80x9cbondingxe2x80x9d of the metal powder layers facing one another is achieved by this process. Moreover, this process makes it possible to arrange additional reinforcing elements in the form of shaped sheet metal parts or profiles before the heating of the sheet metal parts lying one on top of another between these sheet metal parts in certain partial areas of the sandwich component, and these reinforcing elements are connected to the expanded metal powder layer during the subsequent expansion operation in such a way that they cannot be detached without destruction. A sandwich component, which has an especially high moment of resistance in partial areas and which can be manufactured especially inexpensively, is thus obtained.
An exemplary embodiment of the sandwich component according to the present invention will be explained in greater detail below on the basis of the attached drawings and the process for manufacturing the sandwich component will be described.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiment of the invention are illustrated.